ApoA-I synthesis is very sensitive to changes in the distribution of apoA-I among the slow and fast plasma components identified using the compartmental model to describe apoA-I metabolism in normal individuals. In Tangier disease metabolism from the fast plasma component for both homologous and autologous radiolabeled apoA-I is increased resulting in a decresed residence for this apoprotein. Compared to the correlation between free fatty acid levels, VLDL-TG synthesis rates in Pima Indians, diabetic Pima Indians do not have this correlation with their continuously elevated free fatty acids but have a positive correlation between C-petide (insulin) levels and VLDL-TG synthesis rate as determined using compartmental models. Subjects with combined familial hyperlipoproteinemia have increases in both cholesterol and triglyceride synthesis compared to subjects with type IV hyperlipidemia with normal cholesterol and triglyceride synthesis rates but decreased VLDL-TG catabolic rate.